Heavy-duty stabilized camera head with camera position sensing

ABSTRACT

A panhead ( 1 ) having a counterbalance action suitable for heavy cameras or equipment, and provides instantaneous electronic measurements of head settings and position. The improved counterbalance utilizes a dual-tower dual-axis non-linear mechanism as well as position encoders indexed to each axis ( 7 - 13 ) of head movement. Potentiometer setting detectors are also indexed to settable adjustments to read and relay such adjustments, and an electronic display ( 25 ) conveys information regarding the current positions and settings of the camera head ( 1 ). A novel mounting system situated at the top of the head provides for fast and simple mounting and unmounting of equipment or a dutch roll head. In particular, a novel dovetail ( 19, 21 ) engagement mechanism swings a dovetail side down during detachment. In an embodiment of the invention, the dutch roll head can be remotely proportionally actuated by a user via a switch mountable to a handle used for panning and tilting of the pan head.

TECHNICAL FIELD

This invention relates generally to equipment for supporting opticalequipment and, more particularly, relates to a camera head for pivotallysupporting a camera in a counterbalanced manner.

BACKGROUND OF THE INVENTION

Cameras have been and continue to be critical components in both motionpicture and television feature production. An important criterion forthe use of a camera in television or motion picture capture tasks is theability to smoothly follow an action item, such as an athlete, with thecamera. However, cameras usable in motion picture and television workare typically heavy and cumbersome to manipulate. For example, astandard television camera may weigh 100 pounds or more. Thus, in orderfor a camera to be manipulable so as to provide such smooth operation,it is desirable to balance the weight and inertia of the camera and tomitigate the effects of minor unintended forces on the camera by theoperator.

In order to stabilize the motion of a camera on a camera head, it istypical to employ drag mechanisms. One such prior art drag mechanism isillustrated in U.S. Pat. No. 4,955,568 (“the '568 patent”) to O'Connoret al, entitled “Panhead For Camera,” which is assigned to the assigneeof the present invention and is hereby incorporated by reference in itsentirety for all that it teaches. In particular, the '568 patentillustrates an adjustable fluid drag mechanism. It is useful for cameraoperators to have ready access to data describing the various dragsettings for the camera, so as to accurately adjust such settings and tobe able to accurately reproduce a desired setting at a later time.However, the mechanism illustrated in the '568 patent does not providefor the rapid collection and display of measurement data relating to thedrag forces set by the operator. Other prior art mechanisms have alsonot provided integral mechanisms for sensing drag settings and quicklyconveying such settings to the camera operator in a unified way. Rather,prior art techniques have generally employed visual mechanicalmechanisms that do not provide the level of accuracy, repeatability, andease of use desirable in the motion picture industry.

Generally, counterbalance measures have been utilized to balance theweight of the camera about the tilt axis. An example of aspring-operated counterbalance technique is described in the '568patent, previously incorporated by reference in its entirety. Othercounterbalance techniques have been employed as well. For example,counterbalances using linear springs or cam and roller architectureshave sometimes been employed.

However, prior art counterbalance techniques generally function wellonly for small to medium tilt angles. While the counterbalance mechanismdisclosed in the '568 patent functions over a tilt angle of ±90° anddesirably exerts a sinusoidal restoring torque, none of the prior arttechniques, including that of the mechanism disclosed in the '568patent, are adapted and ideally suited for heavier cameras. Many of thecameras in use today for motion picture and television filming work,however, may far exceed 200 pounds in weight. For that reason, aheavy-duty counterbalance mechanism adapted to accommodate thecounterbalance loads produced by such equipment is needed.

Additionally, prior art mechanisms for attaching a camera or otherequipment unit to a camera head are not suitable for use with heavyequipment. That is, they do not provide sufficient ease of attachmentand detachment for cameras that are cumbersome due to extreme weight.For example, a typical sliding dovetail connection requires a user toslide a heavy object along a precise axis while holding the object leveluntil support is achieved. Even systems that permit one side of thedovetail base to drop away for camera removal still require manualintervention by the user to force the dropping side down.

In addition, it is often desirable for a camera operator or film editorto know the position of the camera throughout a shot or sequence inorder to reproduce a scene or to coordinate special effects with theactual footage taken. The prior art, however, has not included means bywhich the camera operator could readily ascertain and thereby reproducethe exact position of the tripod and camera.

Accordingly, it is a general object of the invention to provide animproved camera panhead that smoothly pans and tilts while allowinginstantaneous capture and display of camera position and drag settinginformation. A more specific object is to provide a head that providesthe instantaneous electronic capture and display of the camera positionand movement.

It is a further object of the invention to provide an improved camerapanhead that is able to provide nonlinear counterbalance action forheavy cameras or other equipment throughout a wide range of tilt angles.

It is a further object of the invention to provide a camera head thatallows easy and accurate adjustment of the counterbalance and dragsettings.

It is a further object of the invention to provide an improved camerahead that allows for the natural and uncomplicated mounting and removalof heavy cameras or other equipment to the panhead.

SUMMARY OF THE INVENTION

The invention embodies in general terms an improved camera panhead thatprovides counterbalance action suitable for heavy cameras or equipment,and that provides instantaneous electronic measurements of head settingsand position. The improved counterbalance utilizes a novel dual-towerdual-axis non-linear mechanism to provide sufficient restoring force andintegrity to support heavy camera equipment, while still beingrelatively lightweight. The improved camera head also provideshigh-accuracy absolute position rotary encoders indexed to each axis ofhead movement, as well as potentiometer setting detectors indexed tosettable adjustments. In this manner, both camera positions andparameter adjustments may be electronically captured, recorded, anddisplayed to the user.

A conveniently placed electronic display conveys information regardingthe current state of the camera head. In particular, a digital LCDgraphical user interface is located on the head and displays informationrelating to the position of the head and the position of the headadjustment settings such as drag and counterbalance settings. Thedigital display is part of an electronics module that also containsvarious electrical inputs and outputs. A remote display module may beconnected to the electronics module via a cable to remotely display to auser data relating to the head.

A mounting platform situated at the top of the head provides for fastand simple mounting and unmounting of heavy equipment. In particular, anovel dovetail engagement mechanism provides for compressive force by amovable dovetail side during attachment of the camera. However, thenovel dovetail engagement mechanism also swings the dovetail side downand away from the dovetail platform during detachment to facilitate easyremoval of the camera or other heavy equipment from a dovetail base.

A dutch roll head attachment is mountable upon the mounting platform andis adapted to receive the camera, thus providing an additional axis ofcamera movement as well as positional information.

An embodiment of the invention comprises a panhead for supportingequipment and providing movement from a vertical position to a tiltposition, said panhead comprising, in combination, a tilt housing, atilt drum defining a tilt axis, said tilt drum being mounted within saidhousing for rotation about said tilt axis, at least four springs, saidsprings forming at least two separate pairs of springs, mounted insubstantially perpendicular planes to said tilt axis, a common axisdisposed substantially parallel to the tilt axis, at least one mount formounting one end of each of said springs pivotally along a commonhorizontal axis, said common axis lying below said tilt axis in avertical plane containing said tilt axis, whereby the end of one springin each pair of springs coupled to the common axis is mounted betweenthe ends of the other pair of springs coupled to the common axis, thespring pair mountings to the common axis being staggered, and aplurality of mounts for coupling the opposite ends of each pair of saidsprings to the tilt drum for rotation therewith, said pairs of springsbeing mounted at an angle to a substantially vertical plane containingthe tilt axis when said panhead is in said vertical position, wherebysaid springs exert a restoring torque when the tilt drum is tilted fromsaid vertical position to said tilt position. An embodiment of theinvention further comprises a vertical pan shaft defining a vertical panaxis, and a base housing for mounting said tilt housing on said verticalpan shaft for rotation about said vertical pan axis. An embodiment ofthe invention further comprises a first integral rotary sensor disposedwithin the tilt housing and adapted to sense rotation of the tilt drumabout the tilt axis and output a first signal indicative of the rotationof the tilt drum about the tilt axis. An embodiment of the inventionfurther comprising a second integral rotary sensor disposed within thebase housing and adapted to sense rotation of the tilt housing about thepan axis and output a second signal indicative of the rotation of thetilt housing about the pan axis. An embodiment of the invention furthercomprises a display unit for displaying a first display related to therotation of the tilt drum about the tilt axis and a second displayrelated to the rotation of the tilt housing about the pan axis, whereinthe first and second displays are derived from the first and secondsignals respectively. An embodiment of the invention further comprises aroll head mounted to the panhead for rotation of the supported equipmentfor rotation of the supported equipment about a roll axis, the displayunit further comprising an input for receiving a third signal indicativeof an amount of roll about the roll axis experienced by the roll headmounted to the panhead, and a third display related to the amount ofroll about the roll axis experienced by the roll head, wherein the thirddisplay is derived from the third signal.

In an alternate embodiment of the invention comprises a panhead forsupporting equipment and providing movement from a vertical position toa tilt position, said panhead comprising, in combination, a tilthousing, a tilt drum defining a tilt axis, said tilt drum being mountedwithin said housing for rotation about said tilt axis, at least foursprings, said springs forming at least two separate pairs of springs,mounted in substantially perpendicular planes to said tilt axis, acommon axis disposed substantially parallel to the tilt axis, at leastone mount for mounting one end of each of said springs pivotally along acommon horizontal axis, said common axis lying below said tilt axis in avertical plane containing said tilt axis, whereby the end of one springin each pair of springs coupled to the common axis is mounted betweenthe ends of the other pair of springs coupled to the common axis, thespring pair mountings to the common axis being staggered, and aplurality of mounts for coupling the opposite ends of each pair of saidsprings to the tilt drum for rotation therewith, said pairs of springsbeing mounted at an angle to a substantially vertical plane containingthe tilt axis when said panhead is in said vertical position, wherebysaid springs exert a restoring torque when the tilt drum is tilted fromsaid vertical position to said tilt position, a vertical pan shaftdefining a vertical pan axis, and a base housing for mounting said tilthousing on said vertical pan shaft for rotation about said vertical panaxis, the panhead further comprising a first integral rotary sensordisposed within the tilt housing and adapted to sense rotation of thetilt drum about the tilt axis and output a first signal indicative ofthe rotation of the tilt drum about the tilt axis, the panhead furthercomprising a second integral rotary sensor disposed within the basehousing and adapted to sense rotation of the tilt housing about the panaxis and output a second signal indicative of the rotation of the tilthousing about the pan axis, the panhead further comprising a displayunit for displaying a first display related to the rotation of the tiltdrum about the tilt axis and a second display related to the rotation ofthe tilt housing about the pan axis, wherein the first and seconddisplays are derived from the first and second signals respectively, thedisplay unit further comprises a plurality of further displays fordisplaying at least an indication related to the restoring torqueexerted about the tilt axis when the tilt drum is tilted from anequilibrium position.

In an alternate embodiment of the invention, a panhead for supportingequipment and providing movement from a vertical position to a tiltposition comprises, in combination, a tilt housing, a tilt drum defininga tilt axis, said tilt drum being mounted within said housing forrotation about said tilt axis, at least four springs, said springsforming at least two separate pairs of springs, mounted in substantiallyperpendicular planes to said tilt axis, a common axis disposedsubstantially parallel to the tilt axis, at least one mount for mountingone end of each of said springs pivotally along a common horizontalaxis, said common axis lying below said tilt axis in a vertical planecontaining said tilt axis, whereby the end of one spring in each pair ofsprings coupled to the common axis is mounted between the ends of theother pair of springs coupled to the common axis, the spring pairmountings to the common axis being staggered, and a plurality of mountsfor coupling the opposite ends of each pair of said springs to the tiltdrum for rotation therewith, said pairs of springs being mounted at anangle to a substantially vertical plane containing the tilt axis whensaid panhead is in said vertical position, whereby said springs exert arestoring torque when the tilt drum is tilted from said verticalposition to said tilt position, the panhead further comprising avertical pan shaft defining a vertical pan axis, and a base housing formounting said tilt housing on said vertical pan shaft for rotation aboutsaid vertical pan axis, the panhead further comprising a pan dragassembly for exerting a drag force against rotation of the housing onsaid vertical pan shaft about said vertical pan axis, the panheadfurther comprising a tilt drag assembly for exerting a drag forceagainst rotation of the tilt drum, and a display unit for displaying anindication related to an amount of drag force exerted against rotationof the tilt drum about the tilt axis or the tilt housing about the panaxis. In another embodiment of the invention, the panhead furthercomprises a roll head mounted to the panhead for rotation of thesupported equipment about a roll axis, the display unit furthercomprising a roll display for displaying an indication related to anamount of drag force exerted against rotation of the roll head about theroll axis.

Another embodiment of the invention further comprises a dovetail mountfor retaining a removable dovetail rail, the dovetail mount beingadapted to secure the removal dovetail rail to a panhead of an equipmentsupporting device, the dovetail mount comprising: a pair of opposeddovetail sides forming a dovetail track, at least one of said dovetailsides being movable; a movable locking lever; and an actuable couplingmechanism extending between the movable dovetail side and the lever;said locking lever being movable in a first direction for pressing themovable dovetail side toward the opposed dovetail side, therebyretaining the removable dovetail rail, said locking lever being movablein a second direction to move the movable dovetail side away from theopposed dovetail side in a horizontal plane, movement of the lockinglever past a threshold point in the second direction further acting tolower the movable dovetail side through the horizontal plane, allowingthe removable dovetail rail to be disengaged from the dovetail track. Inanother embodiment, the actuable coupling mechanism comprises a cammingarrangement to lower the movable dovetail side through the horizontalplane.

Another embodiment of the invention comprises a dovetail mount forretaining a removable dovetail rail, the dovetail mount being adapted tosecure the removal dovetail rail to a panhead of an equipment supportingdevice, the dovetail mount comprising: a pair of opposed dovetail sidesforming a dovetail track, at least one of said dovetail sides beingmovable; a movable locking lever; and an actuable coupling mechanismextending between the movable dovetail side and the lever; said lockinglever being movable in a first direction for pressing the movabledovetail side toward the opposed dovetail side, thereby retaining theremovable dovetail rail, said locking lever being movable in a seconddirection to move the movable dovetail side away from the opposeddovetail side in a horizontal plane, movement of the locking lever pasta threshold point in the second direction further acting to lower themovable dovetail side through the horizontal plane, allowing theremovable dovetail rail to be disengaged from the dovetail track, theactuable coupling mechanism comprising at least one movable armpivotably coupling the locking lever to the movable dovetail side at afirst pivot axis, and the camming arrangement comprises a catch and atleast one trip lever pivotably coupled at a second pivot axis, said triplever being disposed to engage said catch as said locking lever is movedpast said threshold point in the second direction, said trip leverrotating about said second pivot axis to exert a force on said movabledovetail side to rotate the movable dovetail side about said first pivotaxis to lower the movable dovetail side through the horizontal plane. Inanother embodiment, the trip lever is pivotably coupled to the movabledovetail side.

Another embodiment of the invention a dovetail mount for retaining aremovable dovetail rail, the dovetail mount being adapted to secure theremoval dovetail rail to a panhead of an equipment supporting device,the dovetail mount comprising: a pair of opposed dovetail sides forminga dovetail track, at least one of said dovetail sides being movable; amovable locking lever; and an actuable coupling mechanism extendingbetween the movable dovetail side and the lever; said locking leverbeing movable in a first direction for pressing the movable dovetailside toward the opposed dovetail side, thereby retaining the removabledovetail rail, said locking lever being movable in a second direction tomove the movable dovetail side away from the opposed dovetail side in ahorizontal plane, movement of the locking lever past a threshold pointin the second direction further acting to lower the movable dovetailside through the horizontal plane, allowing the removable dovetail railto be disengaged from the dovetail track, the actuable couplingmechanism comprising at least one movable arm pivotably coupling thelocking lever to the movable dovetail side at a first pivot axis, andthe camming arrangement comprises a catch and at least one trip leverpivotably coupled at a second pivot axis, said trip lever being disposedto engage said catch as said locking lever is moved past said thresholdpoint in the second direction, said trip lever rotating about saidsecond pivot axis to exert a force on said movable dovetail side torotate the movable dovetail side about said first pivot axis to lowerthe movable dovetail side through the horizontal plane, the catch beingsecured to the movable dovetail side.

Another embodiment of the invention further comprises a dovetail mountfor retaining a removable dovetail rail, the dovetail mount beingadapted to secure the removal dovetail rail to a panhead of an equipmentsupporting device, the dovetail mount comprising: a pair of opposeddovetail sides forming a dovetail track, at least one of said dovetailsides being movable; a movable locking lever; and an actuable couplingmechanism extending between the movable dovetail side and the lever;said locking lever being movable in a first direction for pressing themovable dovetail side toward the opposed dovetail side, therebyretaining the removable dovetail rail, said locking lever being movablein a second direction to move the movable dovetail side away from theopposed dovetail side in a horizontal plane, movement of the lockinglever past a threshold point in the second direction further acting tolower the movable dovetail side through the horizontal plane, allowingthe removable dovetail rail to be disengaged from the dovetail track,the dovetail mount further comprising at least one pair of mating rackand pinion gears secured to the removable dovetail rail and the dovetailtrack, whereby the position of the removable dovetail rail within thedovetail track can be adjusted by rotating the pinion before fixing theremovable dovetail rail to the dovetail track.

Another embodiment of the invention comprises a quickly detachablebattery power source including at least one battery having two terminalsfor powering electric functions of a panhead, the battery power sourcecomprising; first and second leads adapted to be electrically coupled tothe battery terminals; a housing for holding at least one said battery,said housing having a first end and a second closed end; and a closurefor placement at the first end of the housing after insertion of the atleast one battery, such that prior to fixed placement of the cylindricalclosure at the first end of the housing, a voltage difference is notmeasurable across the first and second leads, and a voltage differenceis measurable across the first and second leads after fixed placement ofthe closure at the opening of the housing. In another embodiment of theinvention, fixed placement of the closure at the first end of thehousing requires application of first force along an axis of thehousing, followed by application of a second force along an angulardirection relative to the axis of the housing, whereby the closureresists removal forces applied along the axis of the housing. Anotherembodiment of the invention includes an electronic panhead displaypackage for displaying a readout corresponding to at least one angulardisplacement associated with a panhead, comprising such a battery powersource and further comprising a processing unit and a backup powersource, so that if the cylindrical closure is removed from thecylindrical housing, the backup power source will supply electricalpower temporarily to the processing unit.

Another embodiment of the invention comprises a method for coupling abattery power source to a panhead to power electrical functions of thepanhead, the method comprising the steps of providing a battery powersource having a housing and having a first lead disposed at an end facethe housing and a second lead extending from a side surface of thehousing, linearly advancing the end face into engagement with thepanhead, and rotating the battery housing to engage the leads withelectrical connections of the panhead.

Another embodiment of the invention comprises a dutch roll head forproviding a roll function to a camera, the dutch roll head beingremotely actuable by a user, comprising:a roll axle disposed along aroll axis; a motor connected to the roll axle for causing rotationthereof about the roll axis; and a user grip adapted for mounting on ahandle, whereby the grip may be used to move the handle; and anelectronic interface element mounted on the user grip linked to themotor via an electronic link and adapted to be actuated by said user,whereby when said user actuates the interface element by a given amount,a signal is transmitted via the electronic link to the motor causing themotor to effect a rotation of the roll axle in an amount proportional tothe given amount by which the user actuates the interface element.Another embodiment of the invention comprises such a dutch roll headwherein the interface element is selected from the group consisting of asliding switch, a rotary switch, and a toggle switch.

Additional features and advantages of the invention will be madeapparent from the following detailed description of illustrativeembodiments, which proceeds with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

While the appended claims will set forth the features of the presentinvention with particularity, the invention, together with its objectsand advantages, may be best understood from the following detaileddescription taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 is a perspective view of a camera panhead according to teachingsof the present invention;

FIG. 2 a is a cross sectional side view of a tilt axis counterbalancemechanism;

FIG. 2 b is a partial cross sectional top plan view of the tilt axiscounterbalance mechanism with the housing removed;

FIG. 3 is a cross sectional top view of the tilt axis counterbalanceadjustment mechanism;

FIG. 4 a is a perspective view of a dutch roll head attachment accordingto an embodiment of the present invention for use atop a panhead;

FIGS. 4 b-d are side views of a dutch roll head attachment according toan alternative embodiment of the present invention for use atop apanhead according to an embodiment of the invention, wherein the dutchroll head is shown in varying degrees of adjustment;

FIG. 4 e is a perspective view of a dutch roll head attachment accordingto an alternative embodiment of the present invention for use atop apanhead according to an embodiment of the invention.

FIG. 5 is a perspective view of an electronic module including a digitaldisplay according to an embodiment of the present invention;

FIG. 6 is a perspective view of an adjustable drag inducing mechanismaccording to an embodiment of the invention;

FIG. 7 is a perspective view of gearing used to actuate the tilt axiscounterbalance mechanism according to an embodiment of the invention;

FIG. 8 is a fragmentary perspective view of a disc and associatedoptical pick-up for measuring camera position within an embodiment ofthe invention;

FIG. 9 is a cross sectional side view of the tilt axis drag inducementand position measurement mechanisms;

FIG. 10 is a cross sectional side view of the pan axis drag inducementand position measurement mechanisms;

FIG. 11 is a partial cross sectional side view of a dutch roll headattachment according to an embodiment of the invention, showing draginducement, position sensing, and optional counterbalance locations;

FIG. 12 a is a cross sectional side view of a quick-change battery packin an assembled position according to an embodiment of the invention;

FIG. 12 b is an exploded cross sectional side view of the quick-changebattery pack in a disassembled position according to an embodiment ofthe invention;

FIG. 13 is an exploded perspective view of the quick-change battery packin a disassembled position according to an embodiment of the invention;

FIG. 14 is a partially exploded perspective view of an improved dovetailcamera mounting system according to an embodiment of the invention;

FIG. 15 is a cross sectional bottom view of the improved dovetail cameramounting system according to an embodiment of the invention;

FIG. 16 a is a fragmentary, partial cross sectional side view of adovetail side lowering mechanism according to an embodiment of theinvention with a dovetail side in a mating relation with a matching sideof a dovetail platform;

FIG. 16 b is a fragmentary, partial cross sectional side view of thedovetail side lowering mechanism according to an embodiment of theinvention with the dovetail side in a withdrawn relation from thematching side of the dovetail platform;

FIG. 16 c is a fragmentary partial cross sectional side view of thedovetail side lowering mechanism according to an embodiment of theinvention with the dovetail side in a withdrawn and lowered relationwith the matching side of the dovetail platform; and

FIG. 17 is a schematic diagram of a remote dutch roll head controlsystem according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Turning to the drawings, wherein like reference numerals refer to likeelements, the invention is illustrated as being implemented inaccordance with teachings of the invention in a panhead as shown inFIG. 1. FIG. 1 shows a perspective view of a panhead 1 according to anembodiment of the invention. The illustration of FIG. 1 is generalized,and is intended to convey to the reader the general features and usageof the panhead in accordance with this embodiment. The panhead 1consists of a base 3 that is mountable to a tripod or other support,that in turn rests upon the ground or floor. The remainder of thepanhead, that is from housing 5 upward, is pivotable about a pan axis 7that runs substantially through the center or central region of the base3. This motion is damped and sensed, as will be discussed hereinafter.Locking lever 9 is operable to lock the panhead so that it does not moveabout the upright pan axis 7. It will be appreciated that the placementof this lever or any other control is not critical. Thus, for example,lever 9 may alternatively be located in a symmetric location on theopposite side of the head 1.

A housing 11 covers mechanisms related to the pivoting of the panheadabout a tilt axis 13, the mechanisms running substantially horizontallythrough the center or central region of housing 11. The motion of thehead 1 about this axis is also sensed and damped as will be discussedhereinafter. Locking lever 17 is operable to lock the head to preventmovement about tilt axis 13.

Situated at the top of the head 1 are structures to facilitate themounting of a camera or other equipment to the head 1. In particular, adovetail base 19 is fixed to the housing 11, while a dovetail platform21 is fixable to the dovetail base 19 via two dovetail sides, one ofwhich 23 is visible in FIG. 1, the other of which is symmetricallysituated on the opposite side of the dovetail platform 21. Rather thanmounting a camera directly to the dovetail base 19 via the dovetailplatform 21, it is also possible to mount the camera to anotherattachment such as a dutch roll head as described herein, which is thenmounted to the dovetail base 19.

It will be appreciated that the placement of a heavy camera atop thehead 1 will create a significant downward force in the direction of panaxis 7 when the camera is situated directly over the tilt axis 13. Itwill be further appreciated that any deviation of the center of gravityof the camera from pan axis 7 will result in an increasing torsionalload about tilt axis 13 as the deviation increases. Thus, when a cameraor other instrument supported on the platform 21 (or a dutch head) isthen tilted about the tilt axis 13, a significant and nonlinearrestoring force is required to counterbalance the camera so that theoperator is not required to constantly exert force to prevent the camerafrom pulling itself downward around tilt axis 13. In accordance with animportant aspect of the invention, the head 1 is provided with aheavy-duty nonlinear counterbalance mechanism.

Referring to FIG. 2, the counterbalance mechanism according to anembodiment of the invention is shown. FIG. 2 a shows a sectional sideview of the counterbalance mechanism taken along tilt axis 13, whileFIG. 2 b shows a cut-away top view of the mechanism taken along pan axis7, the tilt drum 14 having been removed. It will be appreciated that thetilt drum 14 defines a tilt axis about which it rotates. While thestructure described herein is novel, the basic principle of operation ofthe counterbalance mechanism itself remains substantially the same asdescribed in the '568 patent to O'Connor et al., previously incorporatedby reference. Accordingly, the function will be described only inoverview except for those portions that differ. For a more completeunderstanding of the geometrical principles involved during use of thehead, the reader is invited to read the '568 patent, paying particularattention to the discussion of FIGS. 6-10.

Referring to FIG. 2 a, the lower portion of the panhead can be seen, aswell as the dovetail base 19 for supporting equipment atop the head 1.As described in greater detail in the '568 patent, the wiffle trees 201,203 capture springs 205 in such a manner as to compress the springs moreor less depending upon the position of the base 19 as the head istilted. The reader is referred to FIGS. 8-10 of the '568 patent for adiscussion of the forces in play during tilting of the head.Essentially, the nonlinear deformation of the springs 205 creates anonlinear counterbalancing force to counter the nonlinear torsionalforce applied by the weight of the camera on the head during tilting.

However, for large heavy cameras, such as those weighing 200 pounds ormore, the counterbalance force that the springs 205 must exert becomesimmense. This creates a need for very powerful springs, each capable ofexerting a restoring force of approximately 1000 pounds or more, but theuse of such powerful springs tends to place large loads on thestructural components of the head such as the rods 211 supporting thetrees 201, 203. Additionally, the force required to adjust thecounterbalance force by adjusting the position of the common rod 213 isgreatly increased generally in proportion to the increase in springstrength.

The solution of the present invention is to employ strong yet compactcompression springs, adapted to meet the large loads imposed, and beingdisposed in a novel arrangement to avoid damage to other components ofthe head. In particular, in order to minimize the weight of the finishedhead, it is desirable to use hollow steel rods 211, 213, produced from4130 heat-treatable alloy steel or other high strength steel or alloy.The reason for using hollow steel rods is that other lightweight metalssuch as aluminum typically do not possess the structural strength ofheavier metals such as stainless steel, chrome molybdenum alloys, andother alloys.

Even so, in order to reduce the weight of the head while accommodatingthe structural loads imposed by the strong springs used, it is desirableto reduce the permissible size of the rods by arranging the springloading to reduce the exerted rod bending moment. Referring to FIG. 2 b,an exemplary wiffle tree arrangement according to the present inventionis shown. In particular, the illustrated arrangement is devised tominimize bending moments by minimizing the distance between oppositelyacting force centers on the most susceptible elements, i.e. rods 211,213.

Two support towers 215, 217 for the common rod 213 are provided,approximately symmetrically placed on rod 213, extending downward in thedirection of pan axis 7. It will be appreciated that the dual towerarrangement is also particularly suitable for use in an application suchas this, where extremely high force springs are utilized. The bendingmoment applied to the common rod 213 is reduced by providing the dualsupport towers 215, 217, thus reducing the necessary size and weight ofthe common rod 213. To readily adjust for equipment of varied weights,these towers are vertically adjustable to adjust the position of thecommon axis or rod 213. This way, the operator may adjust thecounterbalance force provided (according to the basic principles setforth in the '568 patent, already incorporated herein by reference inits entirety).

The spring assemblies are arranged as shown, so that the support towersare placed between oppositely extending wiffle tree and springassemblies, which are disposed at an angle with respect to pan axis 7.Additionally, the wiffle trees and support towers are disposed in arelationship that minimizes the bending moments, and, therefore,stresses along the shafts. More specifically, the wiffle tree pairingsare identical, rather than mirror images of each other across the centerof the head along the tilt axis as in the prior art. That is, the wiffletrees are disposed in a staggered fashion as opposed to symmetricallyabout a central support tower, as disclosed in the '568 patent. In thisway, the two central wiffle tree assemblies place the greatest bendingload on their respective wiffle tree support rods 211. However, unlikethe prior art, the other wiffle tree assembly on each support rod 211provides minimal additional bending load because each is placed adjacenta support point, i.e. end wall 207 or end wall 209. With respect to theloads experienced by common rod 213, the bending loads are alsominimized by the illustrated configuration. In particular, lower wiffletree supports 203 are placed so as to minimize the distance between themand any adjacent support points such as support towers 215, 217 or endwalls 207, 209. In addition, the close spacing of opposing lower wiffletree supports 203 minimizes the local twisting moment resulting frompairs of oppositely directed horizontal force components applied on rod213 by adjacent lower wiffle tree support pairs. In other words, thestaggered positioning of the wiffle tree supports 201, 203 along therespective support rods 211 and common rod 213 minimize the resultingbending moments exerted by the two centermost wiffle tree supports 201,203.

Note that the foregoing discussion describes a preferred arrangement fortwo pairs of spring assemblies used in counterbalancing, however, thetwo pairs of spring assemblies may alternatively be arranged in anotherconfiguration. Exemplary alternative configurations are shown in FIGS.12 and 13 of the '568 patent (for two spring assemblies) alreadyincorporated herein, and are described in the related discussion in the'568 patent. Given the disclosure herein, one of skill in the art willappreciate that the same mechanisms may be adapted for the use of twopairs of spring assemblies.

FIG. 3 illustrates an exemplary mechanism by which the support towers215, 217 of FIG. 2 may be adjusted upwardly and downwardly along panaxis 7 without the application of undue force by the operator. Inparticular, FIG. 3 illustrates a partial cross sectional view of thepanhead at line A taken along pan axis 7 of FIG. 2 a. It can be seenthat support towers 215, 217 are centered on circular gears 301, 303.Respective threaded shafts 302, 304 fixed to each of gears 301, 303extend perpendicular to each gear's major plane and extend threadablyinto each of support towers 215, 217. Thus, a turning of the gears 301,303 results in a raising or lowering of the support towers 215, 217.Even though this relationship provides a certain leverage advantagedepending upon the thread pitch of the threaded shafts 302, 304 fixed tothe circular gears 301, 303, the strength of the springs 205 is suchthat greater leverage may be needed by many human operators.Accordingly, the gears 301, 303 are driven and coordinated viarespective worm gears 305, 307, attached to a common shaft 309. Thus, inaccordance with an important feature of the invention, the rotation ofthe common shaft 309 results in the substantially identical,simultaneous movement of the support towers 215, 217. A further gearreduction is provided by a spur gear 311 attached to shaft 309 andindexed to a pinion gear (not visible in this view). One exemplarygearing arrangement will be discussed in greater detail below withrespect to FIG. 7.

The pinion gear is attached to a common shaft 315 that also carries ahandle 313 that may be manipulated by an operator. The handle alsopreferably further includes an exposed socket on a common axis with theshaft 315, allowing the handle to be alternatively turned via anelectric screwdriver or other rotary tool. This feature may aid theoperator when there is insufficient time to turn the handle by hand therequired number of turns to provide the necessary counterbalance.

It will be appreciated that rotation of the handle 313 will cause arotation of gears 301, 303, and a subsequent coordinated raising orlowering of support towers 215, 217. In turn, the raising or lowering ofthe towers compresses the springs 205 to a greater or lesser degree,providing varying degrees of nonlinear counterbalance force to counterthe tilting of the head about tilt axis 13.

To provide a third degree of movement and adjustment, a dutch roll headmay optionally be used in conjunction with the panhead. A dutch rollhead rotates about a third axis, typically referred to as the roll axis.A roll axis is one that is substantially parallel with the camera sightline axis, although the two need not be co-linear. FIG. 4 illustrates aroll head assembly 401. The roll head 401 comprises a base 403 fixableto the top of the panhead previously discussed by for example a dovetailmount, and pivotally fixed to roll platform 405 at roll axis 407. Rollaxis 407 preferably coincides with camera axis 409, although it issufficient that both axes are simply substantially parallel.

According to an important feature of the invention, however, the centerof gravity of the mounted camera and roll platform 405 is disposed alongthe roll axis 407. In this way, the equipment balance of the head 1remains unaffected by the roll of the equipment mounted on the dutchroll head 401. In order to facilitate adjustment of the height ofplatform 405, both to assure necessary clearance with the base 403 andto place the center of gravity of the platform 405 and camera along theroll axis 407, the platform 405 is movable up and down in the directionof axis 415. The base 403 is illustrated as being slotted to permit rod413 to be moved vertically. However, other techniques for allowingvertical movement may also be used. For example, the platform 405 may bevertically movable with respect to rod 413. In any case, the movement ofthe platform 405 alone or the platform 405 and rod 413 is linearlyconstrained, as along a dovetail mount or along a track made of tworods.

While alternative mechanisms may be used to allow vertical movement ofthe platform 405, a rack and pinion, screw, or other suitable mechanismis preferably employed to reduce the force needed to adjust the positionof the camera and platform 405. Such mechanism may be hand-operated,such as via a crank or other actuator. Alternatively, the mechanism maybe motorized, such as thru the use of an electric motor geared tocontrollably alter the vertical position of the camera and platform 405,as will be appreciated by those of skill in the art. An exemplary gearedvertical adjustment mechanism is illustrated in FIG. 3 for adjusting thecounterbalance force, and a similar mechanism can be used for any othervertical adjustment such as for adjustment of the roll head.Additionally, a lock 417 is provided so that the platform 405 may befixed in the desired position. The lock may employ compression ofdovetail sides, or may use any other mechanism such as a setscrew with aknob head.

A handle 411 is preferably fixed to platform 405 via shaft 413, theshaft 413 being coaxial with roll axis 407 and usable to pivot theplatform 405 about the roll axis 407. Within base 403, severalmechanisms are preferably attached to shaft 413. In particular, it maybe desirable to provide an adjustable counterbalance mechanism on shaft413 to laterally counterbalance the camera weight using the sameprinciples discussed above to provide counterbalance on the tilt axis.Such counterbalance will, however, typically not be required if thecamera center of gravity is placed as described above. Additionally, adrag mechanism is preferably indexed to shaft 413 within base 403 so asto allow for smooth camera movement about the roll axis 407. Theseelements will be discussed in greater detail hereinafter. The base 403may be fixed to the panhead using any suitable mechanism, but it ispreferable that attachment be by way of the dovetail platform to bediscussed in greater detail below.

The degree of roll attainable depends upon the dimensions of the camera,in that interference between the camera and the base 403 will determinethe limits of travel. Base 403 preferably exposes other controls usableto affect the roll behavior of the camera. In particular, such controlspreferably include a lock 417 to prevent roll movement of the cameraabout the roll axis, and a drag adjustment 419 to adjust the amount ofdrag about the roll axis 407. A mechanical drag indicator 421 may alsobe exposed on base 403, and/or an electrical output may supply the draginformation along with counterbalance adjustment information ifcounterbalance is used, and encoded roll position information. Ifcounterbalance is used, base 403 preferably also exposes acounterbalance adjustment control as discussed with respect to the tiltaxis counterbalance mechanism.

An alternative dutch roll head arrangement is shown in FIGS. 4 b-d. Aswith the previously discussed embodiment, a base 425 is provided forattachment to a head as described herein or otherwise. The basecomprises or is attachable to a first socket 427 for receiving ahorizontal support tube 429. A second socket 431 also receiveshorizontal support tube 429. Each of sockets 427 and 431 are fixable inrelation to horizontal support tube 429 via a clamping actionfacilitated by bolts 433 and 435 respectively, or otherwise. Secondsocket 431 has a perpendicularly oriented third socket 437 fixed theretofor receiving a perpendicularly oriented vertical support tube 439. Aclamping bolt (not shown) is usable to fix the vertical support tubewith respect to the third socket 437, in a similar fashion as bolts 431and 433.

In order to further couple a roll head support 441 to the base 425, afourth socket 443 is secured to the roll support 441 and fixed atop thevertical support tube 439 via the fourth socket 443, and via a clampingaction provided by a clamping bolt 445. The roll head support 441rotatably supports an axle 447 having a roll handle 449 optionallycoupled thereto on one side. The handle 449 may be disposed in a hole inaxle 447 and fixed in place via a set screw 451, although otherattachments are envisioned. On the other side of the roll head support441, the axle 447 is attached to a roll platform 453, to which isattached, via screws or otherwise, a camera base 455. A camera 457 ismounted to the camera base 455. It will be appreciated by those of skillin the art that dutch rotation or roll of the roll platform 453, camerabase 455 and the camera 457 will occur about the axis 461 defined byaxle 447. In this embodiment, an axis 459 including the center ofgravity of the camera 457, the camera base 455 and the platform 453 isconveniently illustrated as coinciding with the sight line 459 of thecamera. Thus, those of skill in the art will appreciate that it isdesirable to align the axis 459, which includes the center of gravity,and, here, the sight line, with the dutch rotational axis 461.

FIG. 4 b illustrates a possible initial mounting position of the cameraand the elements of the dutch head before adjustment of the roll axis.FIGS. 4 c-d illustrate further adjustments to better align the axis ofthe center of gravity 459 of the camera (about which no gravitationaltilt moment is exerted) with the roll axis 461 about which axle 447rotates. As shown in FIG. 4 c, the roll platform 453 is first raisedvertically so that the central gravitational axis 459 of the camerasubstantially coincides with the roll axis 461 of the roll head 441.This adjustment may be allowed and then fixed via a set screw or othermeans, fixing the roll platform 453 in relation to the axle 447.Subsequently as shown in FIG. 4 d, the camera is lowered (to attain alowest possible center of gravity for stability) while maintaining theregistration between the central axis 459 of the center of gravity andthe camera and the roll axis 461 of the roll head assembly. This is doneby loosening the clamping bolt (not shown) associated with socket 437and lowering vertical support member 439 until further substantialadjustment would cause interference between the roll platform 453 andany other member of the dutch roll head or of a pan head to which thedutch roll head may attached. After adjustment, the clamping boltassociated with socket 437 is retightened. Note that the alternativedutch roll head shown in FIGS. 4 b-d preferably embodies all the sametilt locks, sensors, indicators, outputs, drag adjustment mechanisms,etc. as the head shown with reference to FIG. 4 a.

Further, note that the vertical adjustment mechanisms described withrespect to FIG. 4 a may likewise be applied to the roll head arrangementshown in FIGS. 4 c-d. For example, the vertical movement of the platform453 and base 455, and accordingly the camera 457 may be geared due tothe extreme weight of the camera 457, and such gearing may be actuatedeither manually, such as via a crank, or automatically such as via ageared electric motor. By way of further example, a gearing mechanismthat can be either manually actuated, or driven by a power screw driveror the like may be provided. Alternately, a drive motor may be provided.It will be appreciated that the various mounting and adjustments mayalso be provided in accordance with the spirit and teaching of theinvention.

An alternative roll platform adjustment mechanism is shown in FIG. 4 e.In particular, the roll platform 461, which is pivotable about the rollaxis 465 at axle 463, is vertically adjustable via a slide 467 retainedwithin a rectangular tube 469. The fit between the slide 467 and thetube 469 is preferably such that the slide cannot move substantially inlateral dimensions, but may move vertically within the tube 469 foradjustment. Additionally, as with the other embodiments, the cameraplatform 471 is adjustable fore and aft, such as in a direction parallelto the roll axis 465, and is also adjustable laterally, or side-to-side.In this manner, the center of gravity of the camera and platform may beadjusted so that they do not exert a roll moment or a tilt moment. Suchfore and aft and lateral adjustment is preferably, but not necessarily,effected by way of a dovetail slide and mount disposed along eachdirection. Once the vertical, fore and aft, and lateral positions of thecamera are set, the movement of the platform in each dimension ispreferably lockable so that the balance of the camera package does notchange during use.

Referring now to FIG. 17, an optional motor drive and actuator for thedutch roll head is shown schematically. In this embodiment, a useractuated actuator grip 1701 is mountable on a handle, such as a panhandle, usable to pan the camera on the pan head as described elsewhereherein. The grip 1701 may be mounted by clamps, friction fit, orotherwise. For example, the grip may have a cavity 1703 that cooperateswith the exterior of a tubular handle to secure the grip 1701 to thehandle.

The grip 1701 is electrically connected to a motor 1705. A switch 1707on the grip 1701 allows the user to actuate the motor in eitherdirection, and preferably at a rate that is proportional to the userinduced displacement of the switch 1707, such as by sliding, toggling,or rotation. The motor 1705 is geared to an axle 1711 at the roll axis,such as axle 413 of FIG. 4 a, such that the actuation of the motor 1705causes the roll platform, and hence the camera package, to roll aboutthe tilt axis. The gearing of the motor to the tilt axle may be by beltdrive, chain drive, or geared drive, and preferably should use reductiongearing both to allow the motor to more easily adjust the roll, and toallow greater precision of movement. Note that the other functions ofthe roll head, such as position measurement through a rotary encoder1709, are preferably employed within this embodiment as well.

Using the actuator grip as described above, a user can pan, tilt, androll the camera package using only one hand. This provides a smoothercamera operation and eases the task of the camera operator.Additionally, the user's other hand can then be used to actuate otherdesired functions, such as drag adjustment, axis locks, and so on.

The mechanisms for adjusting the drag on each axis will now bediscussed. As mentioned previously, providing a certain amount of dragon a given axis of rotation will tend to smooth the movement about thataxis, eliminating camera overshoot and unsteadiness. Because cameras andoperators differ greatly, it is desirable to provide an adjustmentmechanism whereby the amount of drag may be preset or modified. The '568patent, already incorporated by reference in its entirety, discloses thebasic principle of viscous drag mechanisms, and the reader is referredto that patent for a full discussion of such mechanisms. The presentinvention utilizes the basic principles set forth in that patent, bututilizes an improved mechanism to actuate the drag sectors.

Referring to FIG. 6, a schematic view of an exemplary viscous dragmechanism 601 is shown. The drag assembly 601 includes a number of dragsector assemblies 603 and a drag disc assembly 605. The drag sectorassemblies 603 are mounted so as to be movable linearly along a radiusof the drag disc assembly 605. The individual stacked discs 619 of thedrag disc assembly 605 are fixed to a shaft 607. In this way, when theshaft 607 rotates, the drag disc assembly 605 rotates as well.

The individual elements 619 of each of the drag sector assemblies 603are appropriately fixed relative to each element 619 in a given dragsector assembly 603 by rods and spacers 620 or other appropriatemechanism. The individual elements 619 in turn are interleavably relatedto the drag disc assembly 605. In turn, the drag sector assemblies 603are actuated in a coordinated fashion by gears 609 which are manipulatedby a user through a knob 621 or other mechanism. Thus, as the user turnsthe adjustment knob 621, the drag sector assemblies 603 becomesymmetrically more or less interleaved with the drag disc assembly 605depending upon the direction in which the knob 621 is turned. Note thatalthough a direct connection is shown between knob 621 and gear 609, anyalternative actuating arrangement may be used. For example, the knob 621may drive a worm, which drives a worm gear, which is geared to gear 609.

The spaces between stacked discs 617 of the drag disc assembly 605,between the stacked individual elements 619 of the drag sectorassemblies 630, and between the stacked discs 619 and individualelements 619 are filled with a viscous fluid. A greater level ofinterleaving will create a stronger viscous drag on the drag discassembly 605 and hence on the shaft 607. Likewise, a lesser degree ofinterleaving will lessen the amount of drag associated with the rotationof shaft 607. The reader is referred to the '568 patent and U.S. Pat.No. 3,822,769 to O'Connor, hereby incorporated by reference in itsentirety for all that it teaches, for a fuller discussion of thedrag-producing interaction and environment.

The gears 609 are coordinated by interceding gears, chain and cogs, orother suitable mechanism for coordinating their movement, so that theassemblies 603 move symmetrically with respect to disc 605. Although twodrag sector assemblies 603 are shown for clarity, any number of suchassemblies may be employed. In another embodiment, only one such dragsector assembly and one such disc 605 are provided for each axis. Inthis presently preferred embodiment, the drag sector assemblies 603 eachcomprise 23 sector pieces 619 with 22 spacer elements (see 620) locatedbetween the sector pieces 619, and each disc 605 comprises 22 discelements 617 spaced apart by 21 spacer elements (not visible) alongshaft 607.

Having described the mechanical aspects of the invention in detailabove, the electrical features of the panhead according to the inventionwill now be discussed. In accordance with an important feature of theinvention, the position of the panhead 1 with regard to the degree whichthe mounted equipment is rotated about the pan axis 7, and/or tiltedabout the tilt axis 13, and/or the dutch head roll axis 461 may bedirectly read by the user. In this way, a given shot may be recorded orread for later duplication, for example, or for special effects appliedbased upon a given position of the equipment. In overview, theelectrical features provided facilitate the measurement and reporting ofcamera position and adjustment settings. Other electrical features suchas backlighting for camera level indicators are also preferablyprovided. In order to electronically sense the position of the panhead1, rotary encoders are positioned within housings 5 and 11 (and dutchroll head, if utilized), as will be discussed more fully hereinafter.The sensed positions are converted to electronic data digitallydisplayable on graphical user interface panel 25 (as shown, for example,in FIG. 1). The electronic module 27 of which the graphical userinterface 25 is a part also preferably comprises buttons and switchesusable to interact with the module to control features of the display orother features such as head level backlights, as well as electricalinputs and outputs.

FIG. 5 illustrates an exemplary graphical user interface for allowing anoperator to observe measurement data and to affect the operation of theelectronic features. Note that all measurement data may also oralternatively be fed to the camera or image storage device itself, sothat the camera position will be stored in direct association with thecaptured image at any point in time. Panel 501 is part of electronicsmodule 503. In addition to the panel 501, the electronics module 503also exposes electrical contacts, preferably LEMO connectors, forproviding and receiving electrical power and signals. Within module 503are standard electrical circuits to receive, convey, and processinformation to provide the indicated outputs and displays.

More specifically, panel 501 comprises a power button or switch 505 forturning on and off the power to the electronics module 503. Anotherbutton or switch 507 is operable to turn on and off certain lights. Suchlights may be, for example, back-lights, such as LEDs used to enhancethe readability of liquid bubble level devices mounted on the head whichare usable to level the camera on one or more axes.

Further, panel 501 also comprises display elements related to theposition of each axis as well as the drag setting for each axis and anycounterbalance setting for each axis. Thus, for example, row 509displays information related to the roll axis, such as head angle 511 onthe roll axis, drag setting 513 for the roll axis, and counterbalancesetting 515 for the roll axis. A reset button 517 is preferably providedfor each axis to allow the operator to set the current angle as zero, sothat subsequent angle measurements may be taken from that point. Thedisplay rows for the tilt 519 and pan 529 axes expose the same featuresand functionality, keeping in mind that a given axis may omit certainfeatures. For example, it will not be typical to provide acounterbalance or associated counterbalance adjustment reading for thepan axis, but such may be provided.

The LEMO connector ports exposed by the electronics module preferablyinclude a 5 volt auxiliary power input 521, a computer output 523, aremote output 525, and a roll head input 527. Although batteriestypically power the electronics module, the 5 volt auxiliary power input521 allows the operator to optionally power the electronics module viaan external 5 volt DC power source. The computer output 523 provides theinformation collected and displayed in the form of a digital data streamto be received by a separate computer through a serial port orotherwise, so that the positions and settings of the head may be trackedand stored in the computer. The remote output 525 outputs head positionand setting data in a digital or analog form usable by a remote displaymodule. This function allows the operator to attach a remote displaymodule to the remote output 525 via a cable and to place the remotedisplay module in a location where the operator may conveniently viewand/or record all or some of the data available on the panel 501. Forexample, the operator may place the remote display module adjacent tothe camera eyepiece via an adhesive or mechanical connection forconvenient and instantaneous viewing of head data.

While those of skill in the art will readily appreciate how to configurethe circuitry of the electronics module to provide the desired behavior,certain features will be expressly set forth for the convenience of thereader. The electronic components within the electronics module may beplaced on separate circuit boards, but it has been found that the use ofa single dual sided circuit board is more compact and robust.Furthermore, it is desirable to backlight the panel 501. It has beenfound that an ideal way to provide such backlight is to illuminate theends of a plurality of fiber optical cables, and terminate thenon-illuminated ends of such cables at the back of the LCD display thatprovides the display information at panel 501. While the electronicsmodule may be mounted on any part of the head, it has been found thatthe most convenient location for mounting the module is on the main bodyabove the joint between the stationary base 3 and the housing 5, asillustrated in FIG. 1.

In order to sense the position of the drag sector assemblies 603, apotentiometer 611 is associated with the gears 609. In one exemplaryarrangement, a gear 615 is fixed to the shaft 613 of the potentiometer611. This gear 615 mates with one of the gears 609 so that rotation ofgears 609 causes a rotation of the shaft 613 of the potentiometer 611.In this way, the resistance exhibited by the potentiometer 611 gives anindication of the current position of the drag sector assemblies 603,and hence of the level of drag currently experienced by shaft 607. Inanother embodiment, the shaft 613 of the potentiometer is directlyattached to the shaft of a gear 609, providing a corresponding ratherthan simply proportional reading. The electrical outputs of thepotentiometer 611 are supplied to the electronic module 503, for use inderiving a digital representation of the current drag.

The electronic module 503 also comprises two potentiometer adjustmentsfor each drag assembly in order to adjust the indication of drag givenso that it travels from at or near 0% for the minimum amount of dragapplied, to at or near 100% for the maximum amount of drag applied. Inparticular, as those skilled in the art of electronics will appreciate,one factory settable potentiometer is provided to adjust the percentageindicated when the drag sector assemblies 603 are minimally interleaved,while a second factory settable potentiometer is provided to adjust theslope of the percentage indicated as a function of the amount ofinterleaving. In this way, the percentage of drag indicated on panel 501can be adjusted so that minimal interleaving yields a reading at or near0% while maximum interleaving yields a reading at or near 100%.

A drag mechanism such as that described above is placed on each axis, sothat the shaft 607 is rotated coincident with rotation on the relevantaxis. Likewise, the drag adjustment setting on each axis is relayed tothe electronic module 503 and is displayed in the appropriate locationon the panel 501.

The remaining mechanisms usable to collect data for display on panel 501will now be discussed in greater detail. Turning first to FIGS. 3 and 7,gears 301, 303 are driven via respective worm gears 305, 307, attachedto a common shaft 309, and a further gear reduction is provided by aspur gear 311 attached to shaft 309 and indexed to a pinion gear.Referring to FIG. 7, a portion of the above gearing arrangement is shownin greater detail. Like numerals indicate like components, i.e.,elements 709, 711, 713, and 715 of FIG. 7 correspond to elements 309,311, 313, and 315 of FIG. 3.

The gearing arrangement of FIG. 7 provides for an electronic reading ofthe counterbalance position in the following manner. When knob 713 isrotated, in turn rotating pinion 717 and consequently spur 711, thecounterbalance support towers 215, 217 are raised or loweredaccordingly, adjusting the degree of counterbalance applied. At the sametime, worm gear 719 fixed to common shaft 715 is rotated. This causesmating gear 725, fixed to the shaft 723 of potentiometer 721, to rotateas well, changing the resistance of the potentiometer 721. The leads ofthe potentiometer 721 are supplied to the electronic module 503 in orderto give an indication of counterbalance applied on the relevant axis.Each axis that is counterbalanced has an associated potentiometer formeasuring the counterbalance position as, for example, described above,and a corresponding display is provided at panel 501. As described abovewith respect to the calibration of drag position indication, eachposition measuring potentiometer is associated with two calibrationpotentiometers in the electronic module 503, usable to calibrate theindication of counterbalance displayed on panel 501.

Within an embodiment of the invention, the position of the head itselfis measured and displayed to the user via panel 501. In this case, it isdesirable to use precision rotary encoders rather than simple resistancemeasurements because greater accuracy may thus be obtained. Exemplaryrotary encoders are commercially available. For example, theHigh-Sensing Accuracy Optical Photo Interpreter, part number GP1A35RV,sold by SHARP ELECTRONICS may be used to encode the movement of anappropriately slotted disc. FIG. 8 schematically illustrates the basicconfiguration of a rotary encoder in use. An encoder disc 801 isattached to a shaft or other rotation center of interest so that thedisc rotates when the rotation center rotates. Typically, the rotationcenter and the disc 801 are arranged to remain in a fixed angularrelation to one another, although the disc may also be geared up or downto the rotation center of interest. The disc is perforated with slots803 that are typically approximately several thousandths of an inch wideand deep. For example, the slots 803 provided with the GP1A35RV are 2thousandths of an inch wide and 2 thousandths deep, corresponding to theaxial thickness of the disc at the location of a slot.

A pick-up 805 having a slot 807 is situated such that the sides 809, 811of the slot are in a straddling relationship with the disc 801. One ormore light sources such as LEDs or laser diodes reside within one of thesides 809, while one or more light detection devices such as photodiodesor other devices reside in the other side 811. The light source andlight detection devices are situated so that light from a light sourcein side 809 passing through a slot 803 is detected by a light detectiondevice in the other side 811. In this manner, the motion of the disc isdetected electronically and an indication of the motion is transmittedon leads 813. It is preferable that the disc 801 and pick-up 805combination selected also detect the direction of movement of the disc801. In addition, although the preferred encoding mechanism operates vialight transmission, other systems, such as those that operate usingreflectance rather than transmission may also be used. Also, thedescribed encoders are absolute encoders as are preferable for bestaccuracy. However, other types of encoders such as relative encoders mayalso be used alternatively.

An encoder disc/pick-up combination such as that described above ispreferably placed on each axis of movement for which it is desired todisplay position information. Preferably, position information isdisplayed for each axis, i.e. the roll, tilt, and pan axes. FIG. 9 showsa schematic cross section of a panhead according to an embodiment of theinvention in the plane defined by axes 7 and 13 of FIG. 1, at the levelof axis 13. Housing 901 and shaft 903 define a first annular cavity 907centered about shaft 903, while housing 901, endplate 905, and shaft 903define a second annular cavity 909 centered about shaft 903.

The first annular cavity 907 contains an adjustable drag mechanism asdiscussed with respect to FIG. 6. In particular, an annular drag discassembly 915 is fixed to shaft 903 so as to rotate therewith, while oneor more drag sector assemblies 917 are fixed with respect to the housing901 except that they may be adjusted along a radius of axis 13.Adjustment of these drag sector assemblies 917 affects the dragassociated with the rotation of shaft 903 in the manner described withrespect to FIG. 6.

A slotted encoding disc 911 such as the disc 801 of FIG. 8 resideswithin cavity 909, being fixed upon and co-axial with shaft 903. Apick-up 919 such as pick-up 805 of FIG. 8 is situated within cavity 909as well, being fixed to housing 901 so as to straddle encoding disc 911as the disc rotates. Shaft 903 is also fixed to the tilting componentsof the panhead and defines the axis of tilting.

Accordingly, as the camera is tilted, in turn tilting the tiltingcomponents of the head, shaft 903 rotates in registration with thecamera, causing disc 911 to rotate as well. As disc 911 rotates, theslots of the disc alternatingly pass and block light within the pick-up909, creating an electrical signal indicative of the motion of thecamera about the tilt axis 13. As discussed above, this signal isconveyed via electrical leads to the electronics module 913,corresponding to module 503 of FIG. 5, which then interprets anddisplays the information as a percentage of the range of available tiltmotion. Note that the user may use the reset button for a given axissuch as element 517 in FIG. 5, to set the current camera position as thezero position with respect to which future positions may be measured.

Note that the various cavities defined within the head and roll head maybe changed, so that for example, more of the cavity is defined by onepiece than by another, and so on. The only matter of consequence is thatsuch a cavity somehow be defined. Also, note that the relation betweenthe cavities 907, 909 need not be as shown. For example, the cavities,and associated elements, may be disposed on opposite sides of the head,rather than on the same side, such that one end of the axle 903 isassociated with the drag mechanism, while the other end of the axle 903is associated with the rotary measurement mechanism. Similarly, a tiltbrake and tilt lock if used may be disposed at whichever end of theshaft 903 is convenient, and need not be on the same side as each other.

In a similar fashion, the position information for the other axes ismeasured and conveyed to the electronics module 913 for display. FIG. 10is a cross sectional view of the panhead taken in a plane defined byaxes 7 and 13, viewed at the level of line 29. FIG. 10 schematicallyillustrates an exemplary position sensing mechanism for measuring theposition of the camera about the pan axis 7. In particular, the base1001 is fixed relative to a tripod or other support, while the upperhousing 1011 which supports the remainder of the panhead is rotatablydisposed upon the base 1001 and coupled thereto via a large bolt 1019and washer assembly received in a channel in the upper housing 1011.

A plurality of bearings 1013, 1015, 1017 are preferably employed tominimize the friction of rotation and to bear the considerable weight ofthe camera and the upper portion of the head, all of which can rotateabout axis 7. The bearings 1013 may be any suitable type, such asTimpkin tapered bearings, adapted to support both axial and radialloads. Bearings 1015 are preferably disposed to bear axial loadassociated with the central axle attachment between the upper housing1011 and the base 1001. Suitable bearings for this purpose include anybearing capable of bearing the magnitude and direction of stressapplied, such as Torrington thrust bearings. Bearings 1017 are situatedso as to bear radial loads between base 1001 and the lower part of upperhousing 1011. Note that the bearings 1015 and 1017 provide a balancingload for the preloaded the tapered bearings 1013 in the illustratedarrangement. As will appreciated by those of skill in the art, any othersuitable number, type and arrangement of bearings may be used instead ofthe illustrated configuration.

The base defines two annular cavities 1021 and 1023. The first annularcavity 1021 contains an adjustable drag assembly 1003 similar instructure and operation to that described above with respect to the tiltaxis, the adjustment position of which is measured and displayed asdescribed above. Thus, the cavity 1021 additionally contains a suitableviscous fluid, such as one of the many silicon-based fluids familiar tothose of skill in the art. The second annular cavity 1023 contains anencoder disc 1025 and pick-up 1009, operating in substantially the samemanner as described above with respect to the tilt axis, to measure andrelay the pan axis rotation position for display to the user. Note thatin the illustrated embodiment, the pick-up 1009 rotates with the upperhousing 1011, while the encoder disc 1025 remains fixed relative to thebase 1001. However, those of skill in the art will appreciate thatappropriate relative motion may also be achieved by fixing the pick-up1009 relative to the base and allowing the disc 1025 to rotate with theupper housing 1011.

Note that a pan axis lock may also be employed to lock the rotation ofthe upper housing 1011 relative to the base 1001. This generallyrequires a moving locking piece fixed to the housing 1011 and astationary locking piece fixed to the base 1001. Locking of the pan axisis effected by locking the moving and stationary locking piecestogether. Typically, one locking piece will be a disc and the other adisc clamp or other locking mechanism.

FIG. 11 is a cross sectional view of the roll head attachment taken in aplane defined by axis 407 and vertical axis 421 in FIG. 4 a. Note thatalthough not shown in detail in this figure, the camera is preferablyadjustable both fore and aft and side to side, so that the center ofgravity of the camera exerts neither a roll moment nor a tilt moment.The adjustments may be made by way of sliding dovetails and dovetailmounts or otherwise, as will appreciated by those of skill in the art.The housing 1101, corresponding to housing 403, preferably contains adamping mechanism and a position encoding mechanism, and may alsocontain a counterbalance mechanism. In particular, a first annularcavity 1103 contains an adjustable drag assembly 1105 similar instructure and operation to that described above with respect to the tiltaxis, the adjustment position of which is measured and displayed asdescribed above. A second annular cavity 1107 contains an encoder disc1109 and pick-up 1111, operating in substantially the same manner asdescribed above with respect to the tilt axis, to measure and relay theroll axis rotation position for display to the user.

The housing 1101 optionally defines a third annular cavity 1113,containing an adjustable counterbalance mechanism, preferably of thedesign described above or alternatively as described in the '568 patent.If a counterbalance mechanism is employed to counterbalance the cameraabout the roll axis, its setting is preferably detected, relayed andindicated to the user as described above with respect to the tilt axis.Note that since the roll head attachment is optional, the electricalsignals relating to the damping, counterbalance, and position of theroll head are carried by a separate cable having a male LEMO connectorto be plugged into port 527 of the electronics module 503. Note that theaforementioned features of the dutch roll head are preferably alsoincluded in an embodiment as illustrated in FIGS. 4 b-d.

As discussed above, the electronic features of the panhead typicallyreceive electrical power from a portable battery pack that is affixed tothe head or to the tripod or other support. An exemplary constructionfor the battery pack is illustrated in cross sectional view in FIGS. 12a and 12 b. FIG. 12 a shows the battery pack completely assembled whileFIG. 12 b shows the battery pack completely disassembled. The batterypack is constructed of three mating pieces, a battery holder 1201, afirst top 1203 and a second top 1205. The battery holder 1201 and thefirst top 1203 are made primarily of electrically nonconductive materialsuch as plastic, while the second top 1205 is made primarily ofelectrically conductive material such as aluminum. The battery holder1201 contains a bottom contact 1207 for contacting a bottom battery 1209shown in outline in FIG. 12 a. The bottom contact 1207 is electricallyisolated from the battery holder 1201, but is in electrical contact withpin 1211 via a wire, not visible in these illustrations, when thebattery pack is assembled as in FIG. 12 a.

The pin 1211 in the first top 1203 serves to provide electrical contactbetween the bottom contact 1207 and the body of second top 1205. Acentral contact 1213 in first top 1203 makes electrical contact with thepositive end of the series of batteries within holder 1201 when the packis assembled as in FIG. 12 a. In turn a central contact 1215 in secondtop 1205 makes electrical contact with the central contact 1213 when thepack is assembled as in FIG. 12 a. A spring 1217 allows for varyingtolerance of the placement of the second top 1205 with respect to thefirst top 1203. In this manner, the negative or ground voltage of thebatteries in the pack is exposed to the panhead via top 1205, while thepositive voltage is exposed via contact 1215. Note that contact 1215 iselectrically isolated from top 1205.

The fit and function of the battery pack are illustrated in perspectiveview in FIG. 13 for the convenience of the reader. Elements 1301, 1303,1305, 1311, 1313, and 1315 correspond to elements 1201, 1203, 1205,1211, 1213, and 1215 respectively of FIGS. 12 a and 12 b. It can be seenthat the battery pack described herein allows a user to quickly changebatteries in two different ways. In particular, the user may rotate andpull the holder 1301 to detach it from the first and second tops 1303,1305. Once the batteries in the holder are exchanged for freshbatteries, the user may push and rotate holder 1301 to reassemble thebattery pack. Alternatively, the user may push and rotate both theholder 1301 and first top 1303, disengaging them as a unit from secondtop 1305. In this manner, another assembled holder and first top mayreplace the removed unit to provide fresh electrical power. Preferably,the battery pack is assembled to a panhead using the same steps oflinearly advancing the battery pack toward the panhead, and axiallyrotating the battery pack to make the electrical connections. While theholder 1301 and first and second tops 1303, 1305 are illustrated ascylindrical in shape, it will be appreciated that alternate shapes maybe provided.

Note that in either manner of changing out the battery pack from thepanhead, power to the electronics module will be interruptedmomentarily. For this reason, it is desirable that the electronicsmodule incorporates a capacitor or other electrical energy storagedevice to provide a short period, such as thirty seconds, of reservepower during battery change. While the battery pack is preferablyadapted to accommodate 2 “C” size cells, any other number and size ofcells may equivalently be used.

Because the panhead and related components as described herein aregenerally intended for use with heavy cameras or other equipment,according to another feature of the invention, an improved mechanism formounting the camera to the panhead is provided. In particular, it isdifficult and inconvenient to be forced to slide a heavy camera or rollhead mounted on a dovetail platform completely out of a dovetail basebefore being able to remove it. Even with dovetail bases that wouldallow a dovetail side to be forced down to permit camera removal, theoperator is required to manually force the side down. Unfortunately,clearances are generally such that this is often difficult orimpossible.

In an embodiment of the invention, a novel dovetail base is providedthat allows an operator to automatically lower one dovetail side bysimply moving a lever. FIG. 14 shows a perspective view of the novelbase 1401, with a dovetail platform 1403 mounted. In operation, thedovetail rail assembly or platform 1403 is mounted to the bottom of thecamera or roll head via screw holes 1405, and is then mounted on thedovetail base 1401 by being compressed between dovetail sides 1407shaped to mate with the platform 1403. A lever 1409 is provided and isadapted to compress the dovetail sides 1407 when pushed in one directionB, and to uncompress the dovetail sides 1407 and then drop one of sides1407 when pushed in the other direction A. The platform 1403 is indexedto the base 1401 via a rack and pinion mechanism to be more fullydescribed below. Note that screw holes 1411 are used to attach the rackto the underside of the platform 1403.

FIG. 15 shows a schematic bottom view of the platform 1401, includingone dovetail side 1501 (see also 1407 in FIG. 14). This view is providedso that user may understand the mechanism by which the dovetail sidesare pressed together. Manipulation of lever 1509 can be used to eithercause dovetail side 1501 to move toward and mate with dovetail platform1503, or to cause dovetail side 1501 to move away and downward fromdovetail platform 1503. According to the presently preferred embodiment,one dovetail 1501 of the platform moves to allow placement of thedovetail platform 1403, as explained herein, while the dovetail 1407along the opposite side of the platform 1403 remains stationary. In thisway, the user simply places one edge of the dovetail platform 1403underneath the stationary dovetail 1407, and then activates the oppositedovetail 1501 to clamp the platform 1403 in position.

In particular, as lever 1509 is pushed in a clockwise direction, itexerts a pull force on first link 1521, pivoting lever 1523, to which itis hinged, about pivot 1525, thus exerting a leveraged pull force alongdogbone 1527, which is hinged to lever 1525. Dogbone 1527 in turn pullson and rotates link 1529 clockwise about pivot 1531. This motion causessymmetrical pulling motions by side pieces 1535 and 1533. With the leftportion of the assembly as illustrated, the movement of dogbone 1527causes link 1529 to pivot about pivot point 1531, causing a clamping ordownward motion as viewed on side piece 1535 via short link 1537. Thisclamping motion is transmitted to the opposite side piece 1533 of thedovetail side 1501 by link 1545, which causes link 1563 to rotate aboutpivot 1543 and place a downward clamping force on side piece 1533 viashort link 1539. In this way, the rotation of the lever 1509 clockwisewill compress as dovetail side 1501 exerts a force against dovetailplatform 1503, locking the camera in position with respect to thedovetail base 1561.

Conversely, moving the lever 1509 in a counterclockwise direction servesto move dovetail side 1501 away and downward from dovetail platform1503, effectively allowing the camera and platform 1503 to be simplylifted off the base 1561. The mechanism by which this occurs isillustrated in greater detail in FIG. 16. FIG. 16 shows a schematicpartial cross sectional view of a plane defined by axes 7 and 13 ofFIG. 1. FIG. 16 a shows the mechanism in a compressed position, i.e.,clamped with dovetail side 1601 pressed against a mating surface ofdovetail platform 1603. In this view, it can be seen that dovetail side1601 is pivotally linked to side piece 1635 corresponding to side piece1535 at pivot 1619. Corresponding side piece 1633 is hidden from viewbehind side piece 1635, but acts identically to side piece 1635.

According to one feature of the invention, the dovetail side 1601physically moves outward and downward to allow the dovetail platform1603 to be easily placed and located beneath the stationary dovetailside along the opposite edge of the dovetail platform 1603. In this way,as lever 1509 of FIG. 15 is moved from its compressed position in acounterclockwise direction, the reverse process to that described aboveoccurs; that is, side piece 1635 pushes dovetail side 1601 away fromplatform 1603. The dovetail side 1601 is then physically moved downward,through the horizontal plane by a camming arrangement. In the presentlypreferred camming arrangement, this movement is the result of theengagement of a trip lever 1611 and a trip catch 1613, although othercamming arrangements are likewise within the spirit and scope of theinvention.

As can be seen in FIG. 16 b, as dovetail side 1601 moves away, triplever 1611, which is pivotally mounted to dovetail side 1601 at 1617,slides to engagement with the downward projection of trip catch 1613.Both the trip lever 1611 and the dovetail 1601 are biased upward. Tripcatch 1613 is fixed to base 1561 as shown and does not move withdovetail side 1601. Consequently, as side piece 1635 continues to pushdovetail side 1601 away from platform 1603, trip lever 1611, which canno longer move linearly because it abuts catch 1613, rotatescounterclockwise, exerting a clockwise rotational force on dovetail side1601, forcing it downward, as seen in FIG. 16 c.

The clockwise rotational force depends upon the pivot point 1617 of thetrip lever 1611 being lower than the pivot point 1619 between side piece1635 and dovetail side 1601. Theoretically, the force exerted along linklever 1611 can be resolved into two perpendicular components. Onecomponent 1621 is directed along the line between pivot points 1619 and1617, and this component has no effect and produces no movement. Theother component 1623 is perpendicular to the line between pivot points1619 and 1617, and it is this component that produces the clockwiserotation that moves the side piece 1601 downward from platform 1603.

While the trip lever 1611 has been shown pivotably coupled to the sidepiece 1601 and the trip catch 1613 fixed to the base 1561, it will beappreciated by those of skill in the art that the trip lever couldalternately be pivotably coupled to the base and the trip catch fixed tothe side piece. Under such an arrangement, the trip lever could slidealong the upper surface of the side piece until it engages the tripcatch at which time continued force exertion would cause the side pieceto pivot the dovetail side down and through the horizontal plane. Insuch an arrangement, the pivot axis of the trip lever would be disposedabove, rather than below, the pivot axis of the side piece. These arebut two examples of how such a camming arrangement may be incorporatedto provide the lowering movement of the dovetail side. It is furtherwithin the invention, as will be appreciated by those of skill in theart, to actuate the dovetail side 1601 such that substantial lateralmovement is not required before downward movement of the side 1601commences.

Returning to FIG. 15, once the dovetail platform 1503 is placed on thebase, but before it is locked into position by the force of dovetailside 1501, it is desirable to adjust the position of the camera fore andaft to properly place the camera center of gravity. In the platformaccording to an embodiment of the invention, a pinion gear 1547 is usedto move rack 1549 thus moving the dovetail platform 1503 and attachedcamera. This movement may be provided by way of a rotatable knob 1559,which is coupled to the pinion gear 1547. More specifically, pinion 1547is secured to shaft 1551. A helical gear 1553 is also attached to theshaft 1551 and is also mated to a helical gear 1555. In turn, thehelical gear 1555 is attached to a shaft 1557 that the user may turn byturning attached knob 1559. In this manner, the user may convenientlyuse knob 1559 to move the dovetail platform 1503 fore and aft toproperly place the camera center of gravity once the platform 1503 isresting on but not locked to the base.

It will be appreciated that a new and novel camera panhead, rollhead,mounting system, and power system have been described herein. In view ofthe many possible embodiments to which the principles of this inventionmay be applied, it should be recognized that the embodiments describedherein with respect to the drawing figures are meant to be illustrativeonly and should not be taken as limiting the scope of invention. Forexample, those of skill in the art will recognize that the illustratedembodiments can be modified in arrangement and detail without departingfrom the spirit of the invention. Therefore, the invention as describedherein contemplates all such embodiments as may come within the scope ofthe claims and equivalents thereof.

1. A panhead for supporting equipment and providing movement from avertical position to a tilt position, said panhead comprising, incombination, a tilt housing, a rotatable structure defining a tilt axis,said rotatable structure being mounted within said housing for rotationabout said tilt axis, at least four springs, said springs forming atleast a first pair of springs and a second separate pair of springs,said springs of said first pair of springs being mounted such that thesprings are disposed substantially parallel to one another, said springsof said second pair of springs being disposed substantially parallel toone another, said at least four springs being mounted in planessubstantially perpendicular to said tilt axis, a common axis disposedsubstantially parallel to the tilt axis, a horizontal plane includingsaid common axis, said common axis and said tilt axis defining avertical plane containing both axes, at least one mount for mounting oneend of each of said springs pivotally along said common axis, theopposite ends of the springs being disposed on a same side of thehorizontal plane, said opposite ends of said first pair being disposedone side of the vertical plane and said opposite ends of the second pairbeing disposed on the opposite side of the vertical plane, the ends ofone spring in each pair of springs coupled to the common axis by said atleast one mount being mounted between the ends of the other pair ofsprings coupled to the common axis, such that the ends of the springpairs to the common axis are staggered, and a plurality of mounts forcoupling the opposite ends of each pair of said springs to the rotatablestructure for rotation therewith, said pairs of springs being mounted atan angle to a substantially vertical plane containing the tilt axis whensaid panhead is in said vertical position, whereby said springs exert arestoring torque when the rotatable structure is tilted from saidvertical position to said tilt position.
 2. The panhead according toclaim 1 further comprising an adjustment gearing for controllablypositioning the common axis relative to the tilt axis.
 3. The panheadaccording to claim 2 further comprising a common axle orientedsubstantially along the common axis, the one end of said springs beingcoupled to said common axle, the adjustment gearing further comprisingat least two rotatably mounted vertical threaded shafts, each threadedshaft having an axis of rotation, the axes of the threaded shafts beingsubstantially fixed relative to the tilt axis, the threaded shafts beingthreadably coupled to said common axle whereby rotation of the threadedshafts moves the common axle to vary the distance between the commonaxis and the tilt axis.
 4. The panhead according to claim 3 wherein theadjustment gearing further comprises a synchronizer for rotationallyindexing each screw to the other.
 5. The panhead according to claim 1further comprising a tilt drag assembly for exerting a drag forceagainst rotation of the rotatable structure tilt drum.
 6. The panheadaccording to claim 1 further comprising a vertical pan shaft defining avertical pan axis, and a base housing for mounting said tilt housing onsaid vertical pan shaft for rotation of said tilt housing about saidvertical pan axis.
 7. The panhead according to claim 6 furthercomprising a pan drag assembly for exerting a drag force againstrotation of the tilt housing on said vertical pan shaft about saidvertical pan axis.
 8. The panhead according to claim 6 furthercomprising a first integral rotary sensor disposed within the tilthousing and adapted to sense rotation of the tilt drum about the tiltaxis and output a first signal indicative of the rotation of the tiltdrum about the tilt axis.
 9. The panhead according to claim 8 furthercomprising a second integral rotary sensor disposed within the basehousing and adapted to sense rotation of the tilt housing about the panaxis and output a second signal indicative of the rotation of the tilthousing about the pan axis.
 10. The panhead according to claim 9 furthercomprising a display unit for displaying a first display related to therotation of the tilt drum about the tilt axis and a second displayrelated to the rotation of the tilt housing about the pan axis, whereinthe first and second displays are derived from the first and secondsignals respectively.
 11. The panhead according to claim 10 furthercomprising a roll head mounted to the panhead for rotation of thesupported equipment for rotation of the supported equipment about a rollaxis, the display unit further comprising an input for receiving a thirdsignal indicative of an amount of roll about the roll axis experiencedby the roll head mounted to the panhead, and a third display related tothe amount of roll about the roll axis experienced by the roll head,wherein the third display is derived from the third signal.
 12. Thepanhead according to claim 10 wherein the display unit further comprisesa plurality of further displays for displaying at least an indicationrelated to the restoring torque exerted about the tilt axis when thetilt drum is tilted from an equilibrium position.
 13. The panheadaccording to claim 7 further comprising a tilt drag assembly forexerting a drag force against rotation of the tilt drum, and a displayunit for displaying an indication related to an amount of drag forceexerted against rotation of the tilt drum about the tilt axis or thetilt housing about the pan axis.
 14. The panhead according to claim 13further comprising a roll head mounted to the panhead for rotation ofthe supported equipment about a roll axis, the display unit furthercomprising a roll display for displaying an indication related to anamount of drag force exerted against rotation of the roll head about theroll axis.
 15. A counterbalance for use in exerting a counterbalancingforce when moved from a vertical position to a tilt position about atilt axis, the counterbalance comprising: a rotatable structure that isrotatable about the tilt axis; a common axle that is not rotatable aboutthe tilt axis, said common axle having a common axis which is parallelto the tilt axis; at least two common axle supports supporting thecommon axle; first and second lateral axes disposed along either side ofa vertical plane containing said tilt axis, each said lateral axis beingdisposed parallel to but not collinear with the tilt axis, said firstand second axes being disposed for rotation with said rotatablestructure about the tilt axis; a first pair of compressive springassemblies coupled both to the common axle through a first pair ofcouplings and to said first lateral axis; a second pair of compressivespring assemblies coupled both to the common axle through a second pairof couplings and to said second lateral axis, one of the first pair ofcouplings lying between the second pair of couplings along the commonaxle, and one of the second pair of couplings lying between the firstpair of couplings along the common axle, such that the spring pairmountings to the common axis are staggered; and a first rotary sensorfor sensing the rotation of the rotatable structure about the tilt axis,and for producing an electrical tilt output indicative of the amount anddirection of rotation of the rotatable structure about the tilt axis.16. The counterbalance according to claim 15 wherein the first lateralaxis is disposed a first distance from the common axis, and the secondlateral axis is disposed a seconddistance from the common axis, said thefirst and second distances being substantially equal in the verticalposition, rotation of the rotatable structure from the vertical positionto the tilt position lengthening one said distance and shortening theother said distance such that the compressive spring assemblies producesaid counterbalancing force about the tilt axis, said counterbalancefurther comprising a counterbalance adjustment mechanism including anadjustment that moves the common axle towards or away from the tiltaxis, adjusting the first and second distances to adjust thecounterbalancing force exerted by the compressive spring assemblies. 17.The counterbalance according to claim 15 further comprising a tilthousing external to and enclosing the rotatable structure, the commonaxle, the first and second pairs of compressive spring assemblies, andsaid first rotary sensor.
 18. The counterbalance according to claim 17further comprising a base housing, and a pan axle on a pan axis aboutwhich the tilt housing may rotate, said base housing housing the panaxle.
 19. The counterbalance according to claim 18, further comprisingwithin the base housing a second rotary sensor for sensing the rotationof the tilt housing about the pan axis and for producing an electricaltilt output indicative of the amount of rotation of the tilt housingabout the pan axis.
 20. A counterbalance for use in exerting acounterbalancing force when moved from a vertical position to a tiltposition about a tilt axis, the counterbalance comprising: a rotatablestructure; a tilt axis within said rotatable structure; a common axlewithin said rotatable structure, said common axle having a common axisthat is parallel to the tilt axis; first and second lateral axesdisposed along either side of a vertical plane containing said tiltaxis, each said lateral axis being disposed parallel to but notcollinear with the tilt axis; a first pair of spring assemblies coupledboth to the common axle through a first pair of couplings and at saidfirst lateral axis; and a second pair of spring assemblies coupled bothto the common axle through a second pair of couplings and at said secondlateral axis, one of the first pair of couplings lying between thesecond pair of couplings along the common axle, and one of the secondpair of couplings lying between the first pair of couplings along thecommon axle, such that the spring pair mountings to the common axis arestaggered; one of either the common axle or the first and second lateralaxes being rotatable about the tilt axis, the other being rotatablyfixed relative to the tilt axis whereby said spring assemblies exertsaid counterbalancing force during such rotation.
 21. The counterbalanceof claim 20 wherein said common axle is rotatable about the tilt axis,and said first and second lateral axes are rotationally fixed relativeto the tilt axis.
 22. The counterbalance of claim 20 wherein said commonaxle is not rotatable about the tilt axis, and said first and secondlateral axes are rotatable about the tilt axis.